1 /***************************************************************************
2 * Copyright (C) 2005 by Dominic Rath *
3 * Dominic.Rath@gmx.de *
5 * Copyright (C) 2007,2008 Øyvind Harboe *
6 * oyvind.harboe@zylin.com *
8 * This program is free software; you can redistribute it and/or modify *
9 * it under the terms of the GNU General Public License as published by *
10 * the Free Software Foundation; either version 2 of the License, or *
11 * (at your option) any later version. *
13 * This program is distributed in the hope that it will be useful, *
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of *
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
16 * GNU General Public License for more details. *
18 * You should have received a copy of the GNU General Public License *
19 * along with this program; if not, write to the *
20 * Free Software Foundation, Inc., *
21 * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. *
22 ***************************************************************************/
28 #define INCLUDE_JTAG_INTERFACE_H
30 #include "interface.h"
33 * Function bitbang_stableclocks
34 * issues a number of clock cycles while staying in a stable state.
35 * Because the TMS value required to stay in the RESET state is a 1, whereas
36 * the TMS value required to stay in any of the other stable states is a 0,
37 * this function checks the current stable state to decide on the value of TMS
40 static void bitbang_stableclocks(int num_cycles);
43 bitbang_interface_t *bitbang_interface;
45 /* DANGER!!!! clock absolutely *MUST* be 0 in idle or reset won't work!
47 * Set this to 1 and str912 reset halt will fail.
49 * If someone can submit a patch with an explanation it will be greatly
50 * appreciated, but as far as I can tell (ØH) DCLK is generated upon
51 * clk=0 in TAP_IDLE. Good luck deducing that from the ARM documentation!
52 * The ARM documentation uses the term "DCLK is asserted while in the TAP_IDLE
53 * state". With hardware there is no such thing as *while* in a state. There
54 * are only edges. So clk => 0 is in fact a very subtle state transition that
55 * happens *while* in the TAP_IDLE state. "#&¤"#¤&"#&"#&
57 * For "reset halt" the last thing that happens before srst is asserted
58 * is that the breakpoint is set up. If DCLK is not wiggled one last
59 * time before the reset, then the breakpoint is not set up and
60 * "reset halt" will fail to halt.
63 #define CLOCK_IDLE() 0
66 /* The bitbang driver leaves the TCK 0 when in idle */
67 static void bitbang_end_state(tap_state_t state)
69 if (tap_is_state_stable(state))
70 tap_set_end_state(state);
73 LOG_ERROR("BUG: %i is not a valid end state", state);
78 static void bitbang_state_move(int skip)
81 u8 tms_scan = tap_get_tms_path(tap_get_state(), tap_get_end_state());
82 int tms_count = tap_get_tms_path_len(tap_get_state(), tap_get_end_state());
84 for (i = skip; i < tms_count; i++)
86 tms = (tms_scan >> i) & 1;
87 bitbang_interface->write(0, tms, 0);
88 bitbang_interface->write(1, tms, 0);
90 bitbang_interface->write(CLOCK_IDLE(), tms, 0);
92 tap_set_state(tap_get_end_state());
95 static void bitbang_path_move(pathmove_command_t *cmd)
97 int num_states = cmd->num_states;
104 if (tap_state_transition(tap_get_state(), false) == cmd->path[state_count])
108 else if (tap_state_transition(tap_get_state(), true) == cmd->path[state_count])
114 LOG_ERROR("BUG: %s -> %s isn't a valid TAP transition", tap_state_name(tap_get_state()), tap_state_name(cmd->path[state_count]));
118 bitbang_interface->write(0, tms, 0);
119 bitbang_interface->write(1, tms, 0);
121 tap_set_state(cmd->path[state_count]);
126 bitbang_interface->write(CLOCK_IDLE(), tms, 0);
128 tap_set_end_state(tap_get_state());
131 static void bitbang_runtest(int num_cycles)
135 tap_state_t saved_end_state = tap_get_end_state();
137 /* only do a state_move when we're not already in IDLE */
138 if (tap_get_state() != TAP_IDLE)
140 bitbang_end_state(TAP_IDLE);
141 bitbang_state_move(0);
144 /* execute num_cycles */
145 for (i = 0; i < num_cycles; i++)
147 bitbang_interface->write(0, 0, 0);
148 bitbang_interface->write(1, 0, 0);
150 bitbang_interface->write(CLOCK_IDLE(), 0, 0);
152 /* finish in end_state */
153 bitbang_end_state(saved_end_state);
154 if (tap_get_state() != tap_get_end_state())
155 bitbang_state_move(0);
159 static void bitbang_stableclocks(int num_cycles)
161 int tms = (tap_get_state() == TAP_RESET ? 1 : 0);
164 /* send num_cycles clocks onto the cable */
165 for (i = 0; i < num_cycles; i++)
167 bitbang_interface->write(1, tms, 0);
168 bitbang_interface->write(0, tms, 0);
174 static void bitbang_scan(bool ir_scan, enum scan_type type, u8 *buffer, int scan_size)
176 tap_state_t saved_end_state = tap_get_end_state();
179 if (!((!ir_scan && (tap_get_state() == TAP_DRSHIFT)) || (ir_scan && (tap_get_state() == TAP_IRSHIFT))))
182 bitbang_end_state(TAP_IRSHIFT);
184 bitbang_end_state(TAP_DRSHIFT);
186 bitbang_state_move(0);
187 bitbang_end_state(saved_end_state);
190 for (bit_cnt = 0; bit_cnt < scan_size; bit_cnt++)
193 int tms=(bit_cnt==scan_size-1) ? 1 : 0;
196 int bcval=1<<(bit_cnt % 8);
198 /* if we're just reading the scan, but don't care about the output
199 * default to outputting 'low', this also makes valgrind traces more readable,
200 * as it removes the dependency on an uninitialised value
203 if ((type != SCAN_IN) && (buffer[bytec] & bcval))
206 bitbang_interface->write(0, tms, tdi);
209 val=bitbang_interface->read();
211 bitbang_interface->write(1, tms, tdi);
213 if (type != SCAN_OUT)
216 buffer[bytec] |= bcval;
218 buffer[bytec] &= ~bcval;
222 if (tap_get_state() != tap_get_end_state())
224 /* we *KNOW* the above loop transitioned out of
225 * the shift state, so we skip the first state
226 * and move directly to the end state.
228 bitbang_state_move(1);
232 int bitbang_execute_queue(void)
234 jtag_command_t *cmd = jtag_command_queue; /* currently processed command */
240 if (!bitbang_interface)
242 LOG_ERROR("BUG: Bitbang interface called, but not yet initialized");
246 /* return ERROR_OK, unless a jtag_read_buffer returns a failed check
247 * that wasn't handled by a caller-provided error handler
251 if(bitbang_interface->blink)
252 bitbang_interface->blink(1);
259 #ifdef _DEBUG_JTAG_IO_
260 LOG_DEBUG("reset trst: %i srst %i", cmd->cmd.reset->trst, cmd->cmd.reset->srst);
262 if ((cmd->cmd.reset->trst == 1) || (cmd->cmd.reset->srst && (jtag_reset_config & RESET_SRST_PULLS_TRST)))
264 tap_set_state(TAP_RESET);
266 bitbang_interface->reset(cmd->cmd.reset->trst, cmd->cmd.reset->srst);
269 #ifdef _DEBUG_JTAG_IO_
270 LOG_DEBUG("runtest %i cycles, end in %s", cmd->cmd.runtest->num_cycles, tap_state_name(cmd->cmd.runtest->end_state) );
272 bitbang_end_state(cmd->cmd.runtest->end_state);
273 bitbang_runtest(cmd->cmd.runtest->num_cycles);
276 case JTAG_STABLECLOCKS:
277 /* this is only allowed while in a stable state. A check for a stable
278 * state was done in jtag_add_clocks()
280 bitbang_stableclocks(cmd->cmd.stableclocks->num_cycles);
284 #ifdef _DEBUG_JTAG_IO_
285 LOG_DEBUG("statemove end in %s", tap_state_name(cmd->cmd.statemove->end_state));
287 bitbang_end_state(cmd->cmd.statemove->end_state);
288 bitbang_state_move(0);
291 #ifdef _DEBUG_JTAG_IO_
292 LOG_DEBUG("pathmove: %i states, end in %s", cmd->cmd.pathmove->num_states,
293 tap_state_name(cmd->cmd.pathmove->path[cmd->cmd.pathmove->num_states - 1]));
295 bitbang_path_move(cmd->cmd.pathmove);
298 #ifdef _DEBUG_JTAG_IO_
299 LOG_DEBUG("%s scan end in %s", (cmd->cmd.scan->ir_scan) ? "IR" : "DR", tap_state_name(cmd->cmd.scan->end_state) );
301 bitbang_end_state(cmd->cmd.scan->end_state);
302 scan_size = jtag_build_buffer(cmd->cmd.scan, &buffer);
303 type = jtag_scan_type(cmd->cmd.scan);
304 bitbang_scan(cmd->cmd.scan->ir_scan, type, buffer, scan_size);
305 if (jtag_read_buffer(buffer, cmd->cmd.scan) != ERROR_OK)
306 retval = ERROR_JTAG_QUEUE_FAILED;
311 #ifdef _DEBUG_JTAG_IO_
312 LOG_DEBUG("sleep %i", cmd->cmd.sleep->us);
314 jtag_sleep(cmd->cmd.sleep->us);
317 LOG_ERROR("BUG: unknown JTAG command type encountered");
322 if(bitbang_interface->blink)
323 bitbang_interface->blink(0);